Deficient chaperone-mediated autophagy in macrophages aggravates colitis and colitis-associated tumorigenesis in mice

Abstract

Chaperone-mediated autophagy (CMA) is a highly selective form of autophagy responsible for the degradation of specific cytosolic proteins within lysosomes. Recent research has established a significant correlation between CMA and colorectal cancer (CRC). However, the majority of current research focuses on tumor parenchymal cells, with limited attention paid to the expression and role of CMA in tumor stromal cells, particularly in tumor-associated macrophages (TAMs). In this study, we generated myeloid-specific LAMP2A-knockout and knock-in mice to investigate the role of macrophage CMA in dextran sodium sulfate (DSS)-induced colitis and azoxymethane/dextran sodium sulfate-induced CRC. Our findings indicated that the expression of LAMP2A, the rate-limiting component of CMA, was reduced in tumor-associated macrophages of both human and mouse CRC tissues. The knockout of LAMP2A in macrophages exacerbated experimentally induced colitis and colitis-related CRC, whereas its overexpression in macrophages alleviated the progression of colitis and CRC in mice. Notably, we observed increased angiogenesis within the tumor mass of CRC tissues from LAMP2A-mØKO mice. Mechanistically, LAMP2A deficiency elevated the protein levels of HIF-1α, thereby enhancing the secretion of its target genes, vascular endothelial growth factor A and IL-1β, which are 2 important proangiogenic cytokines. Our study suggests that the activation of CMA in macrophages may represent a promising therapeutic strategy for the treatment of CRC.